US9031248B2ActiveUtilityA1
Vehicle engine sound extraction and reproduction
Est. expiryJan 18, 2033(~6.5 yrs left)· nominal 20-yr term from priority
Inventors:Cristian M. Hera
G10K 15/02H03G 3/20
77
PatentIndex Score
6
Cited by
19
References
6
Claims
Abstract
An RPM signal representing a current RPM of a vehicle engine is received. An instant magnitude and an instant phase are determined for each of N harmonics of a target engine sound based on the RPM signal. The instant magnitude and the instant phase are each smoothed to generate a smoothed harmonic magnitude and a smoothed harmonic phase for each of the N harmonics. A magnitude perturbation signal and a phase perturbation signal are generated for each of the N harmonics. An individual harmonic signal is also generated for each of the N harmonics based, at least in part, on the smoothed harmonic magnitude, the magnitude perturbation signal, the smoothed harmonic phase, and the phase perturbation signal. The individual harmonic signals are summed to generate an engine harmonic enhancement signal, and the engine harmonic enhancement signal is transduced to acoustic energy.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1. A method comprising:
in a vehicle engine harmonic enhancement system,
receiving an RPM signal representing a current RPM of a vehicle engine;
based on the RPM signal, determining an instant magnitude, c k (t), for each of N harmonics of a target engine sound by interpolating the instant magnitude, c k (t), from a vector [C k ], wherein the vector [C k ] comprises samples of an RPM-dependent shape, {tilde over (c)} k (RPM), for each of the N harmonics over a subset of RPM values;
based on the RPM signal, determining an instant phase, p k (t), for each of the N harmonics by interpolating the instant phase, p k (t), from a vector [P k ], wherein the vector [P k ] comprises samples of an RPM-dependent phase {tilde over (p)} k (RPM), for each of the N harmonics over the subset of RPM values;
smoothing the instant magnitude, c k (t), to generate a smoothed harmonic magnitude, ĉ k (t), for each of the N harmonics;
smoothing the instant phase, p k (t), to generate a smoothed harmonic phase, {circumflex over (p)} k (t), for each of the N harmonics;
generating a magnitude perturbation signal, dc k (t), for each of the N harmonics;
generating a phase perturbation signal, dp k (t), for each of the N harmonics; and
generating an individual harmonic signal, h k (t), for each of the N harmonics according to: h k (t)=(ĉ k (t)+dc k (t))·sin(2πfl k t+{circumflex over (p)} k (t)+dp k (t));
summing the individual harmonic signals, h k (t), and thereby generating an engine harmonic enhancement signal, he(t) to be added on top of a baseline engine sound; and
transducing the engine harmonic enhancement signal, he(t), to acoustic energy.
2. The method of claim 1 , wherein generating the magnitude perturbation signal comprises generating the magnitude perturbation signal, dc k (t), for each of the N harmonics according to:
d
c
k
(
t
)
=
ncf
k
(
t
)
·
σ
Δ
c
k
σ
ncf
k
,
where σ Δc k , is the standard deviation of fluctuations in the harmonic magnitude of each of the N harmonics of the target engine sound; ncf k (t) is filtered random noise used for generating the magnitude perturbation signal; and σ ncf k is the standard deviation for the filtered random noise used for generating the magnitude perturbation signal.
3. The method of claim 1 , wherein generating the phase perturbation signal comprises generating the phase perturbation signal, dp k (t), for each of the N harmonics according to:
dp
k
(
t
)
=
npf
k
(
t
)
·
σ
Δ
p
k
σ
npf
k
,
where σ Δp k , is the standard deviation of fluctuations in the harmonic phase of each of the N harmonics of the target engine sound; npf k (t) is filtered random noise used for generating the phase perturbation signal; and σ npf k is the standard deviation for the filtered random noise used for generating the phase perturbation signal.
4. An engine harmonic enhancement system, comprising:
a digital signal processor; and
a memory coupled to the digital signal processor and containing instructions that, when executed, cause the digital signal processor to:
receive an RPM signal representing a current RPM of a vehicle engine;
based on the RPM signal, determine an instant magnitude, c k (t), for each of N harmonics of a target engine sound by interpolating the instant magnitude, c k (t), from a vector [C k ], wherein the vector [C k ] comprises samples of an RPM-dependent shape, {tilde over (c)} k (RPM), for each of the N harmonics over a subset of RPM values;
based on the RPM signal, determine an instant phase, p k (t), for each of the N harmonics by interpolating the instant phase, p k (t), from a vector [P k ], wherein the vector [P k ] comprises samples of an RPM-dependent phase {tilde over (p)} k (RPM), for each of the N harmonics over the subset of RPM values;
smooth the instant magnitude, c k (t), to generate a smoothed harmonic magnitude, ĉ k (t), for each of the N harmonics;
smooth the instant phase, p k (t), to generate a smoothed harmonic phase, {circumflex over (p)} k (t), for each of the N harmonics;
generate a magnitude perturbation signal, dc k (t), for each of the N harmonics;
generate a phase perturbation signal, dp k (t), for each of the N harmonics; and
generate an individual harmonic signal, h k (t), for each of the N harmonics according to: h k (t)=(ĉ k (t)+dc k (t))·sin(2πfl k t+{circumflex over (p)} k (t)+dp k (t));
sum the individual harmonic signals, h k (t), and thereby generating an engine harmonic enhancement signal, he(t) to be added on top of a baseline engine sound; and
transduce the engine harmonic enhancement signal, he(t), to acoustic energy.
5. The engine harmonic enhancement system of claim 4 , wherein, when executed, the instructions cause the one or more processors to generate the magnitude perturbation signal, dc k (t), for each of the N harmonics according to:
d
c
k
(
t
)
=
ncf
k
(
t
)
·
σ
Δ
c
k
σ
ncf
k
,
where σ Δc k , is the standard deviation of fluctuations in the harmonic magnitude of each of the N harmonics of the target engine sound; ncf k (t) is filtered random noise used for generating the magnitude perturbation signal; and σ ncf k is the standard deviation for the filtered random noise used for generating the magnitude perturbation signal.
6. The engine harmonic enhancement system of claim 4 , wherein, when executed, the instructions cause the one or more processors to generate the phase perturbation signal, dp k (t), for each of the N harmonics according to:
dp
k
(
t
)
=
npf
k
(
t
)
·
σ
Δ
p
k
σ
npf
k
,
where σ Δp k , is the standard deviation of fluctuations in the harmonic phase of each of the N harmonics of the target engine sound; npf k (t) is filtered random noise used for generating the phase perturbation signal; and σ npf k is the standard deviation for the filtered random noise used for generating the phase perturbation signal.Cited by (0)
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